U.S. Pat. No. 6,040,550 discloses techniques for controlled laser welding of a radial seam at a joint between two membranes of a bellows. An optical tracking device tracks the joint site between the two membranes that are arranged next to each other and rotate about a common axis. The laser beam can be steered such that the laser beam impinges on the outer edge of each of the two membranes to edge weld the rotating membranes at the joint site.
German Patent No. DE 4005314A1 describes a method for micro-soldering with a laser and measuring the soldering spot temperature with a pyrometer camera. The temperature is regulated by a regulating circuit. Through analysis of the actual or nominal signal used in the regulation system, conclusions can be drawn about the solder process or solder errors occurring, which can lead to improved process control on soldering. European Patent No. EP 1371443B1 describes techniques for monitoring laser welds and assessing the weld quality. Radiation produced in the welding area and the power of the laser beam are measured using sensors. The signals measured by the sensors are analyzed and characteristics of the signals are extracted and classified to provide an indication of the quality of the laser weld.